The invention relates to a exchangeable filter cartridge for a liquid filter with an annularly constructed filter medium arranged on a support element. The invention further relates to a liquid filter in which such a filter cartridge is installed.
Filter cartridges of the initially described type are known, for instance, from U.S. Pat. No. 5,413,712. This document describes a filter cartridge comprising a support tube holding the filter medium whose end faces are provided with end disks. This filter cartridge can be replaced by removing a cover from the filter housing. A spring in the cover pushes the installed filter cartridge axially against a centrally arranged outlet port. A sealing membrane provides an axial seal between the outlet port and the end disk of the filter cartridge. The sealing membrane is simultaneously configured as a return flow barrier or check valve.
The disadvantage of the described prior art is the use of a spring to produce an axial force to act against the seal. This spring is an additional component in the filter unit and thus reduces the economic efficiency of the solution. Moreover, the axial force that can be applied by the spring to provide a seal is limited. Increasing the axial force by making the spring stiffer has the disadvantage of increasing the closing forces that have to be applied to the cover, which makes it more difficult to replace the filter element.